Hello, i'm making a 9 rectangle hole picture frame to hold 9 baseball cards. i have cut out the 9 rectangles and used a rabbit router bit with a bearing 1/8th less then the bit to make the indent for the card holder. the problem is that the corners are still rounded. i need to make them square. the piece of wood is 3/4 in. thick and the rabit depth is about 1/2 in. i don't have a mortising machine. is there a tool like a mortising bit that will square up the corner. A chesel seems to want to crack the 1/4 in. good side. Any help please.
Try going with the grain, rather than pushing down from the top, turn the chisel parallel with the frame, and they have to be razor sharp. Look at the chisel end under a light, if you can see a reflection of light it needs to be honed.